var gfilter = {
type: "canvas",
name: "filters",
author: "zhigang",
getInfo: function () {
return this.author + ' ' + this.type + ' ' + this.name;
},
/**
* invert color value of pixel, new pixel = RGB(255-r, 255-g, 255 - b)
*
* @param binaryData - canvas's imagedata.data
* @param l - length of data (width * height of image data)
*/
colorInvertProcess: function(binaryData, l) {
for (var i = 0; i < l; i += 4) {
var r = binaryData[i];
var g = binaryData[i + 1];
var b = binaryData[i + 2];

binaryData[i] = 255-r;
binaryData[i + 1] = 255-g;
binaryData[i + 2] = 255-b;
}
},

/**
* adjust color values and make it more darker and gray...
*
* @param binaryData
* @param l
*/
colorAdjustProcess: function(binaryData, l) {
for (var i = 0; i < l; i += 4) {
var r = binaryData[i];
var g = binaryData[i + 1];
var b = binaryData[i + 2];
binaryData[i] = (r * 0.272) + (g * 0.534) + (b * 0.131);
binaryData[i + 1] = (r * 0.349) + (g * 0.686) + (b * 0.168);
binaryData[i + 2] = (r * 0.393) + (g * 0.769) + (b * 0.189);
}
},

/**
* deep clone image data of canvas
*
* @param context
* @param src
* @returns
*/
copyImageData: function(context, src)
{
var dst = context.createImageData(src.width, src.height);
dst.data.set(src.data);
return dst;
},

/**
* convolution - keneral size 5*5 - blur effect filter(模糊效果)
*
* @param context
* @param canvasData
*/
blurProcess: function(context, canvasData) {
console.log("Canvas Filter - blur process");
var tempCanvasData = this.copyImageData(context, canvasData);
var sumred = 0.0, sumgreen = 0.0, sumblue = 0.0;
for ( var x = 0; x < tempCanvasData.width; x++) {
for ( var y = 0; y < tempCanvasData.height; y++) {
// Index of the pixel in the array
var idx = (x + y * tempCanvasData.width) * 4;
for(var subCol=-2; subCol<=2; subCol++) {
var colOff = subCol + x;
if(colOff <0 || colOff >= tempCanvasData.width) {
colOff = 0;
}
for(var subRow=-2; subRow<=2; subRow++) {
var rowOff = subRow + y;
if(rowOff < 0 || rowOff >= tempCanvasData.height) {
rowOff = 0;
}
var idx2 = (colOff + rowOff * tempCanvasData.width) * 4;
var r = tempCanvasData.data[idx2 + 0];
var g = tempCanvasData.data[idx2 + 1];
var b = tempCanvasData.data[idx2 + 2];
sumred += r;
sumgreen += g;
sumblue += b;
}
}
// calculate new RGB value
var nr = (sumred / 25.0);
var ng = (sumgreen / 25.0);
var nb = (sumblue / 25.0);
// clear previous for next pixel point
sumred = 0.0;
sumgreen = 0.0;
sumblue = 0.0;
// assign new pixel value
canvasData.data[idx + 0] = nr; // Red channel
canvasData.data[idx + 1] = ng; // Green channel
canvasData.data[idx + 2] = nb; // Blue channel
canvasData.data[idx + 3] = 255; // Alpha channel
}
}
},

/**
* after pixel value - before pixel value + 128
* 浮雕效果
*/
reliefProcess: function(context, canvasData) {
console.log("Canvas Filter - relief process");
var tempCanvasData = this.copyImageData(context, canvasData);
for ( var x = 1; x < tempCanvasData.width-1; x++)
{
for ( var y = 1; y < tempCanvasData.height-1; y++)
{
// Index of the pixel in the array
var idx = (x + y * tempCanvasData.width) * 4;
var bidx = ((x-1) + y * tempCanvasData.width) * 4;
var aidx = ((x+1) + y * tempCanvasData.width) * 4;
// calculate new RGB value
var nr = tempCanvasData.data[aidx + 0] - tempCanvasData.data[bidx + 0] + 128;
var ng = tempCanvasData.data[aidx + 1] - tempCanvasData.data[bidx + 1] + 128;
var nb = tempCanvasData.data[aidx + 2] - tempCanvasData.data[bidx + 2] + 128;
nr = (nr < 0) ? 0 : ((nr >255) ? 255 : nr);
ng = (ng < 0) ? 0 : ((ng >255) ? 255 : ng);
nb = (nb < 0) ? 0 : ((nb >255) ? 255 : nb);
// assign new pixel value
canvasData.data[idx + 0] = nr; // Red channel
canvasData.data[idx + 1] = ng; // Green channel
canvasData.data[idx + 2] = nb; // Blue channel
canvasData.data[idx + 3] = 255; // Alpha channel
}
}
},

/**
* before pixel value - after pixel value + 128
* 雕刻效果
*
* @param canvasData
*/
diaokeProcess: function(context, canvasData) {
console.log("Canvas Filter - process");
var tempCanvasData = this.copyImageData(context, canvasData);
for ( var x = 1; x < tempCanvasData.width-1; x++)
{
for ( var y = 1; y < tempCanvasData.height-1; y++)
{
// Index of the pixel in the array
var idx = (x + y * tempCanvasData.width) * 4;
var bidx = ((x-1) + y * tempCanvasData.width) * 4;
var aidx = ((x+1) + y * tempCanvasData.width) * 4;
// calculate new RGB value
var nr = tempCanvasData.data[bidx + 0] - tempCanvasData.data[aidx + 0] + 128;
var ng = tempCanvasData.data[bidx + 1] - tempCanvasData.data[aidx + 1] + 128;
var nb = tempCanvasData.data[bidx + 2] - tempCanvasData.data[aidx + 2] + 128;
nr = (nr < 0) ? 0 : ((nr >255) ? 255 : nr);
ng = (ng < 0) ? 0 : ((ng >255) ? 255 : ng);
nb = (nb < 0) ? 0 : ((nb >255) ? 255 : nb);
// assign new pixel value
canvasData.data[idx + 0] = nr; // Red channel
canvasData.data[idx + 1] = ng; // Green channel
canvasData.data[idx + 2] = nb; // Blue channel
canvasData.data[idx + 3] = 255; // Alpha channel
}
}
},

/**
* mirror reflect
*
* @param context
* @param canvasData
*/
mirrorProcess : function(context, canvasData) {
console.log("Canvas Filter - process");
var tempCanvasData = this.copyImageData(context, canvasData);
for ( var x = 0; x < tempCanvasData.width; x++) // column
{
for ( var y = 0; y < tempCanvasData.height; y++) // row
{
// Index of the pixel in the array
var idx = (x + y * tempCanvasData.width) * 4;
var midx = (((tempCanvasData.width -1) - x) + y * tempCanvasData.width) * 4;
// assign new pixel value
canvasData.data[midx + 0] = tempCanvasData.data[idx + 0]; // Red channel
canvasData.data[midx + 1] = tempCanvasData.data[idx + 1]; ; // Green channel
canvasData.data[midx + 2] = tempCanvasData.data[idx + 2]; ; // Blue channel
canvasData.data[midx + 3] = 255; // Alpha channel
}
}
},
}; 